In the flaskless molding method, an attempt has been made to improve work efficiency by using a well-known flaskless molding machine. For example, Japanese Early-Patent Publication No. 04-66245 suggests that a well-known flaskless molding machine be combined with a pattern change device. The pattern exchanges mechanically and automatically, rather than manually, a used pattern plate that is used to form molds in the molding machine, for a new pattern plate.
However, the flaskless molding machine employed as in the above disclosure is well known, and has also been used in a conventional flaskless molding method, where the pattern plates are exchanged manually. Therefore, this disclosure and the conventional flaskless molding method, where the pattern plates are manually exchanged, are the same as in the processes of forming a pair of mold cavities with the flaskless molding machine. That is, a pattern plate having patterns on both faces is horizontally clamped between a pair of flasks in a sandwich relationship at the side of the molding machine. They are then rotated in unison to a location below a sand supplying device such that they are vertical. Then a pair of opposed squeeze heads is horizontally inserted in the pair of the vertical flasks, which between them clamp the pattern plate, to define a pair of mold cavities. Accordingly, in the conventional flaskless molding machine the processes of forming a pair of mold cavities could not begin until the cope and drag flasks that clamp the match plate therebetween are in the vertical position. Because this situation results in a molding cycle in the conventional flaskless molding machine that still requires much time, the production efficiency of molds is low.